DairyNZ and IrrigationNZ have disputed statements made by Agricultural economist Peter Fraser and farm consultant Dr Alison Dewes who have said claims of farmers being burdened with huge costs from a water tax were overblown.
Fraser and Dewes, using Dairy NZ figures, said there were 12,000 dairy herds in New Zealand consuming 4.8b cubic metres of water.
An average person - based on figures from Wellington, although water use varies nationwide - uses around 80 cubic metres of water, meaning dairy farms alone use the equivalent of around 58.2 million people.
Almost all of the water is used by about 2000 farms, primarily in dry areas such as Canterbury and Otago.
"We've had this huge gold rush to go and convert dry areas to these hugely water intensive uses," Fraser said.
"There's an issue here with how we've gone and used our land. Why have we gone and put these incredibly water hungry uses such as dairy farming in such water scarce areas?
"It's because the water's free."
The average cost of a water tax on an irrigated dairy farm would be between $10,000 and $15,000, their analysis found.
It echoed an analysis by RNZ and Auckland University's Public Policy Institute, which determined the cost to an average irrigated dairy farm would be $13,800.
Dairy NZ has disputed that figure. Trifecta of Taxes